We intend to investigate the mechanism of DNA ejection from bacterial viruses and the transport of that DNA into the cell cytoplasm in preparation for growth and morphogenesis of the next generation of virions. We will isolate mutants in the various proteins, of the virus and the host, involved in this process and identify the genes involved and characterize the actions of their products in carrying out the injection process. We will also investigate the mechanisms of viral recognition of its proper host surface. At this stage we are investigating two specialized interactions involved in that process: the lectinic interaction of the unusual cross-beta protein structure of the phage tail fiber in with the host surface disaccharide and the possible involvement of a specialized Mg++ inhibited ATPase, often associated with movement, in the triggering of the phage baseplate expansion. These experiments are an integral part of our longterm goal of understanding the molecular mechanisms of viral-host recognition and nucleic acid penetration. These processes are often similar in function if not always in mechanism in both bacterial and animal viruses and represent the basis for genetic transfer which is a fundamental mechanism of evolution, both natural and directed.